My wild guess before reading the article: unhealthy food. A big part of which is herbicides and pesticides. I will now read the article.
If anything, food supply in the past 20 years uses a lot less pesticides and herbicides: look at the rise of organic sections in any supermarket. Since 2000 organic food went from niche to mainstream.
See https://www.epa.gov/agriculture/organic-farming - "Pesticides derived from natural sources (such as biological pesticides) may be used in producing organically grown food"